Machines such as, for example, wheel tractor scrapers, dozers, motor graders, wheel loaders, and other types of heavy equipment are used to perform terrain leveling tasks. These machines are often operated over uneven terrain, causing individual wheels to be placed at varying elevations. With a conventional suspension, the machine tilts when its wheels are at varying elevations, resulting in operational difficulties such as reduced traction, productivity, and operator comfort. In addition, conventionally mounted rubber tires function as undampened springs, providing an inadequate response to ground induced vibration and shock.
One method of providing an improved suspension is disclosed in U.S. Pat. No. 4,090,723 (the '723 patent) issued to Hart. The '723 patent discloses a leveling system for a construction vehicle. The construction vehicle has a pair of tandem road-wheels each rotatably mounted on an outer end of a lever arm, which has its inner end pivotally mounted on the frame of the vehicle. A double acting hydraulic cylinder is pivotally interconnected between the lever arms to selectively pivot the road-wheels to adjust the vertical height of one side of the vehicle relative to the other side of the vehicle. Each of the road-wheels is driven by a gear train connected to a driven output shaft of an engine. In one embodiment, the inner end of each lever arm is pivotally mounted at a separate pivot point on the frame of the vehicle. In another embodiment, the lever arms are pivotally mounted at a common pivot point on the frame. In both embodiments, the lever arms are pivotally mounted by annular bearing means on a spindle, inboard of the lever arm. The drive arrangement enables the road-wheel assembly to pivot with respect to the frame in response to an extension or retraction of the cylinder. The drive arrangement thus allows the suspension to function as a wheel leveling system and maintain the vehicle in a level and stable condition when opposing sides of the vehicle rest on different ground levels.
Although the leveling system of the '723 patent may provide an improved suspension, the manner in which the lever arms are mounted may result in undesirable loads on the annular bearing. In particular, because the annual bearing means are inboard of the lever arm, shock on the road-wheel may result in a stress-inducing moment at the annular bearing and spindle. This stress may result in decreased fatigue life of the annual bearing and spindle.
The present disclosure is directed to overcoming one or more of the shortcomings set forth above.